A new and exciting branch of physical and occupational therapies is therapy assisted by a computer-directed robotic arm or device (also called a “manipulator” to distinguish it from the human arm that may engage it, in certain embodiments). The potential benefits of using a manipulator system for tasks such as post-stroke rehabilitative therapy, which typically involves moving a patient's limb(s) through a series of repeated motions, are significant. There exist some types of therapy, such as error-augmentation therapy, that simply cannot be implemented effectively by a human therapist. Furthermore, computer-directed therapy can engage the patient in games, thereby making the experience more enjoyable and encouraging longer and more intense therapy sessions, which are known to benefit patients. Finally, the therapist is able to work with more patients, and is able to offer patients increased therapy duration since the session is no longer constrained by the therapist's physical endurance.
A useful way to categorize robotic rehabilitation systems is by the number of degrees of freedom, or DOFs, that they have. The majority of commercial robotic rehabilitation systems fall into one of two broad categories: low-DOF (typically one to three DOFs) systems which are positioned in front of the patient, and high-DOF (typically six or more DOFs) exoskeleton systems, which are wrapped around the patient's limb, typically an arm or leg. The current approaches for both categories exhibit significant shortcomings, which has contributed to limited realization of the potential of robotic rehabilitation therapies.
Low-DOF systems are usually less expensive than high-DOF systems, but they also typically have a smaller range of motion. Some, such as the INMOTION ARM™ Therapy System of Interactive Motion Technologies of Watertown, Mass., USA, or the KINARM END-POINT ROBOT™ system of BKIN Technologies of Kingston, Ontario, Canada, are limited to only planar movements, greatly reducing the number of rehabilitation tasks that they can be used for. Those low-DOF systems which are not limited to planar movements must typically contend with issues such as avoiding blocking a patient's line of sight, like the DEXTREME™ system of BioXtreme of Rehovot, Israel; providing an extremely limited range of motion, such as with the REOGO® system of Motorika Medical Ltd of Mount Laurel, N.J., USA; and insufficiently supporting a patient's limb. Most of these systems occupy space in front of the patient, impinging on the patient's workspace, increasing the overall footprint needed for a single rehabilitation “station” and consuming valuable space within rehabilitation clinics.
Meanwhile, high-DOF exoskeletal systems, such as the ARMEO® Power system of Hocoma AG of Volketswil, Switzerland, the ARMEO® Spring Spring system of Hocoma AG of Volketswil, Switzerland, and the 8+2 DOF exoskeletal rehabilitation system disclosed in U.S. Pat. No. 8,317,730, are much more complex and consequently generally more expensive than comparable low-DOF systems. While such high-DOF exoskeletal systems usually offer larger ranges of motion than low-DOF systems, their mechanical complexity also makes them bulky, and they typically wrap around the patient's limb, making the systems feel threatening and uncomfortable to patients. Furthermore, human joints do not conform to axes separated by links the way robots do, and the anatomy of every human is different, with different bone lengths and different joint geometries. Even with the high number of axes present in high-DOF systems, fine-tuning an exoskeleton system's joint locations and link lengths to match that of the patient takes considerable time, and even then the system frequently over-constrains the human's limb, potentially causing more harm than good.
Finally, there are a handful of currently available devices which do not fit in either of the two categories listed above: for example, high-DOF non-exoskeletal devices, or low-DOF exoskeletal devices. To date, these devices have generally suffered the weaknesses of both categories, without leveraging the strengths of either. A particularly notable example is the KINARM EXOSKELETON ROBOT™ of BKIN Technologies of Kingston, Ontario, Canada, which is an exoskeletal rehabilitation device designed for bimanual and unimanual upper-extremity rehabilitation and experimentation in humans and non-human primates. Like the KINARM END-POINT ROBOT™ of BKIN Technologies of Kingston, Ontario, Canada, the KINARM EXOSKELETAL ROBOT™ system provides only two degrees of freedom for each limb, limiting the range of rehabilitation exercises that it can conduct. Meanwhile, by implementing an exoskeletal design, the KINARM EXOSKELETAL ROBOT™ device can provide some additional support to the patient's limb, but at the cost of significant increases in device size, cost, complexity and set-up time.
While robot-assisted physical and occupational therapy offers tremendous promise to many groups of patients, the prior art has yet to match that promise. As the previous examples have shown, current therapy devices are either too simplistic and limited, allowing only the most rudimentary exercises and frequently interfering with the patient in the process; or too complex and cumbersome, making the devices expensive, intimidating to patients, and difficult for therapists to use. Thus, there remains a need for a novel device and method that can provide patients and therapists with the ability to perform sophisticated 2-D and 3-D rehabilitation exercises, in a simple, unobtrusive and welcoming form factor, at a relatively low price.